The invention relates to a pressure-actuated power wrench comprising a cylinder bushing within a housing, a piston being displaceable within the housing and reciprocatingly driving an annular piece via a rotatably supported lever.
A power wrench disclosed in U.S. Pat. No. 4,805,496 or U.S. Pat. No. 5,263,388 comprises a housing consisting of a head portion and a driving portion. The driving portion includes an exchangeable cylinder bushing which is introduced, from the interior of the head portion, into a corresponding bore of the driving portion, and is supported on the end wall of the driving portion which faces away from the head portion. The cylinder bushing is mounted from the interior of the head portion. This has to be done prior to the mounting of the lever and the annular member. When the cylinder bushing, which has to withstand very high pressures in the magnitude of 600-800 bar, has become defect, e.g. due to cracking, or when the piston has to be renewed, the entire power wrench has to be dismounted. In this case, the annular member and the lever have to be taken out of the housing first.